Skipping every other element after the first

Question

I have the general idea of how to do this in Java, but I am learning Python and not sure how to do it.

I need to implement a function that returns a list containing

Answer 1

def skip_elements(elements):
  new_list = []
  for index,element in enumerate(elements):
    if index == 0:
      new_list.append(element)
    elif (index % 2) == 0: 
      new_list.append(element)
  return new_list

Also can use for loop + enumerate. elif (index % 2) == 0: ## Checking if number is even, not odd cause indexing starts from zero not 1.

Answer 2

def skip_elements(elements):
   new_list = [ ]
   i = 0
   for element in elements:
       if i%2==0:
         c=elements[i]
         new_list.append(c)
       i+=1
  return new_list

Answer 3

def altElement(a):
    return a[::2]

Answer 4

Using the for-loop like you have, one way is this:

def altElement(a):
    b = []
    j = False
    for i in a:
        j = not j
        if j:
            b.append(i)

    print b

j just keeps switching between 0 and 1 to keep track of when to append an element to b.

Answer 5

def skip_elements(elements):
    # Initialize variables
    i = 0
    new_list=elements[::2]
    return new_list

# Should be ['a', 'c', 'e', 'g']:    
print(skip_elements(["a", "b", "c", "d", "e", "f", "g"]))
# Should be ['Orange', 'Strawberry', 'Peach']:
print(skip_elements(['Orange', 'Pineapple', 'Strawberry', 'Kiwi', 'Peach'])) 
# Should be []:
print(skip_elements([]))

Answer 6

Alternatively, you could do:

for i in range(0, len(a), 2):
    #do something

The extended slice notation is much more concise, though.